Television apparatus



Dec. 22, 1953 H. R. LUBCKE TELEVISION APPARATUS 2 Sheets-Sheet 1 FiledMarch 6, 1950 Ill + lllllllllllliL as INVENTOR.

Dec. 22, 1953 H, R. LUBCKE 2,663,757

TELEVISION APPARATUS Filed March 6, 1950 2 Sheets-Sheet 2 RECEIVER p 55IN VEN TOR Patented Dec. 22, 1953 TELEVISION APPARATUS Harry R. Lubcke,Los Angeles, Calif., assignor to General Teleradio, Inc., Los Angeles,Calif., a

corporation of California Application March 6, 1950, Serial No. 147,835

6 Claims.

This invention relates to color television and more articularly to thesimplification of reproducing apparatus for forming a single colorimage.

The reproducing apparatus as a whole becomes simple when a completecolor image is formed upon substantially a single surface. Applicant hasfurthered this art by devising auxiliary c'rcuitry to act upon a singleelectron stream in the reproducing device, thereby simplifying the videoamplifier by a factor of two-thirds as well as simplifying the deviceitself.

Numerous color systems operate according to the sequential method. Inthis method, only one primary color is reproduced upon the viewingscreen at any one time; whether this be a whole scanning field, a line,or an element along the line.

This invention utilizes the dynamical electron lens and the method ofthe arcuate path for electron streams described in my copendingapplication, Serial No. 137,635. In the present instance, however, onlyone electron gun and one electron stream is used. A deflectioninstrumentality is added which has the effect of sequentially producingelectron streams divergent from the instantaneous axis of normalscanning defiection.

The major object of this invention is to provide simple all-electronicmeans for the sequential reproducing or a color television image.

Another object of this invention is to provide means for causing oneelectron stream to sequentially perform the work of three electronstreams.

Another object of this invention is to remove the need for a multipleelectron gun structure in a color-reproducing cathode ray tube.

Another object of this invention is to eliminate the need for keystonecorrection in such a tube.

Another object of this invention is to cause one video amplifier toperform the work of three video amplifiers of the prior art.

Another object of this invention is to provide a simplecolor-reproducing screen construction.

These and other advantages of the present invention will become apparentfrom the following description and the drawings in which:

Fig. 1 shows a side elevation of one form of the present invention.

Fig. 2 shows a circuit capable of causing sequential divergence of theelectron stream in coaction with deflection means.

Fig. 3 shows waveforms of electrical energy pertinent to the operationof the device of Fig. 2.

Fig. 4. shows an alternate screen construction for the device of Fig. 1,in sectional elevation.

Fig. 5 shows an alternate electronic circuit for accomplishingsequential divergence.

Fig. 6 shows waveforms pertinent to Fig. 5.

In Fig. 1, numeral l indicates a vacuum-tight enclosing envelope. Asingle electron gun 5 is powered by battery 2, or equivalenttransformer-rectifier-filter means, and accomplishes emission of thesingle electron stream 6. Deflecting coils 3 and 4 are located onopposite sides of envelope i and are actuated by source I with a steppedwaveform 3 such that divergent positions of the stream 9 and H! are madeto occur at corresponding instants in the complete color cycle insynchronism with transmitter scanning. Vertical deflecting means l3 andi 4 are also shown as coils on opposite sides of envelope l and areconnected to terminals of the vertical deflection source 25 supplyingwaveform l6. Similarly, coils H and 62, above and below the neck ofdevice i, are connected to horizontal deflection source 25, whichsupplies waveform I1.

Element I5 is a coil of wire surrounding envelope I near transducingscreen 18 (which may be of the fluorescent type), and an essentiallyconstant electric current is caused to flow in this coil, as by batteryl9. This forms a short magnetic electron lens. The ampere-turn valuethereof is adjusted until the electron stream is caused to converge uponan area adjacent to the area of undiverged impingement when the streamis in position 6. Such paths are shown as positions 9 and It in Fig. 1.Because of the different directions of impingement, differenttransducers are impacted, such as a red fluorescing phosphor upon theupper inclined surfaces of the numerous horizontal truncated ridges ofscreen it? by the electron stream when following path 9; greenfiuorescing upon the vertical surface, via path 6, and blue fluorescingupon the lower inclined surface, via path l0. Vertical defiecting coilsI 3 and M are adjusted circumferentially around the neck of the envelopel to align the raster with the ridges of the screen. The truncatedridges are shown large for clarity in exposition.

Fig. 2 shows a typical circuit capable of producing the sequentialdivergence waveform 8 of device l of Fig. 1.

Considering first the dot sequential svstem of color, waveform 69 ofFig. 3 is one of the color commutating waveforms, say the blue. Thiswaveform is produced by the operation of the sampler in the televisionreceiver and the waveform shown corresponds to clipped peaks of a sinewave which have been reversed in polarity by an amplifying stage. It isto be noted that the clipping level is such that the clipped peaksoccupy but one-third of the whole time cycle. Any other waveform may beutilized as long as the relatively steep sided impulses of one-thirdduration can be formed. The waveform appears at terminal 33, of thereceiver.

Capacitor 34 is relatively small in value, of the order of a hundredmicromicrofarads, and res stor 35 is also of small value, of the orderof several thousand ohms. This combination differentiates waveform 68 ofFig. 3, and the waveform results.

In order to carry out the process of this invention, it is necessarythat waveform E! be reversed in phase. This is accomplished by vacuumtube 35 in which the output is taken from the plate load resistor 31 viacoupling capacitor 38.

Waveform 53 is also produced by the operation of the sampler in thetelevision receiver. The throws thereof are spaced differently in timethan those in waveform {iii and correspond to another color in theoperation of the system, such as red. This waveform appears at terminal39 in Fig. 2 and is differentiated by small capacitor All and low-ohmageresistor ii so that waveform 65 results. versed in polarity and soamplifier stage 52 is provided with the output taken from the cathoderesistor 43 via capacitor 44.

The two above-described outputs are combined at the grid resistor 35.The waveform there existent is shown as 55 in Fig. 3. It is thealgebraic sum of waveforms 62 and 65. This combined waveform isamplified by stage 46 and is integrated in the plate circuit thereof.Amplification causes the usual phase reversal, resulting in waveform 66.This waveform does not actually occur in the operating device but can befound to exist as the driving force accomplishing the integration bytemporarily disconnecting capacitor 4B and observing the voltagewaveform at the plate of tube 45. Plate load resistor 41 is relativelylarge in ohmage, and is used essentially as a shunt feed for supplyingthe plate voltage to the vacuum tube. Capacitor 48 is relatively largehaving a small reactance at the operating frequency in relation to theresistance of resistor 47. This arrangement accomplishes integration.The pulses of waveform 86 either add or subtract from the charge oncapacitor 48.

The integrated waveform is shown as 51 and the formation thereof fromwaveform 66 is easily understood. At the beginning of the waveformsequence shown, waveform es includes a pulse of twice the amplitude ofthe pulses of either of waveforms 52 or 64, said pulse being the resultof the addition of two of the prior pulses. From a prior level 68waveform El falls a two-unit decrease in value to point 59. Since thecharge on the capacitor 43 is large with respect to the leakago throughresistor 5?, the level 68 persists until the first positive throw "illin waveform 65 occurs. This increases the charge on capacitor it by oneunit, 1. e. up to point ii. This charge persists until a second positivethrow in waveform 56 increases the charge to the original level inwaveform 6'5, which then persists until the next negative doubleamplitude pulse 12 inwaveform 55 occurs, and the cycle is repeated.

This waveform 6i may be applied directly to the sequential divergencecoils 3 and 4 shown in This waveform is not to be re- Fig. 1, althoughit is usually desirable to increase the energy thereof by means of anamplifier stage identified by vacuum tube 49.

In either event, the waveform output may be applied to the primary of atransformer 5% shown in Fig. 2, in which instance the divergence coils 3and Q are not required.

In this alternate connection, the usual vertical scanning output fromterminals 27 and 2h from source 26 in Fig. 1 is connected to terminals56 and 52 of the second primary of transformer The secondary, havingterminals 53 and 5 5, is connected to the terminals of verticaldeflection coils i3 and M in Fig. 1 and conveys a composite ofwaveforms! 5 and El thereto.

The tricolor sequential video signai exists at terminal 55 in thereceiver of Fig. 2 is connected to the control grid terminal in Fig. 1.

It is to be noted in passing that the device of Fig. 2 will alsooperate. if energized with waveforms and 63 of opposite polarity tothose shown. The output waveform B1 is then of reversed polarity. It isalso possible to interchange the waveforms 66 and 53 with respect toterminals 33 and as. In this instance, also, the Waveform 6'! isreversed in polarity. Finally, should commutating waveform be impressedat terminal 39 which has the throw of original waveform 63 advanced intime one period, the output waveform will be delayed in time one period.

The polarity and direction of winding of coils 3 and l, 13 and I l, orthe transformer connections 29 and 38 can be reversed so that variouscolor sequence and deflection relations can be accomplished.

Fig. 4 shows a novel modification of screen ii in which phosphors orother transducers are deposited upon truncated indentations in thescreen it, instead of upon truncated protuberances. This is a simpleconstruction, being akin to the techniques for making cut glass, eitherthe gen uine article or the manufactured imitation. Electron stream 2!impacts upon inclined surface l5, stream 6 upon surface it, and streamit upon surface ll. Either of the truncated type screens has theadvantage of continuing to reproduce the image, say green, upon thetruncated surfaces, although malfunctioning of the circuitry or otherservice difiiculties to which all receivers are susceptible may occur.The electron stream impinges relatively straight-on to the truncatedsurfaces. Keystone correction, with the possibility of maladjustment, isnot required.

For color systems which change color each line or each frame, analternate circuit for device '5 as shown in Fig. 5 is possible.

In the line sequence method, line synchronizing pulses of negativepolarity produced in the normal functioning of the receiver shown,appear at terminal of Fig. 5. Capacitor 8: blocks the anode potentialfrom the prior amplifier stage and resistor 82 fixes the potential levelwith respect to ground. This waveform isv shown as 95 in Fig. 6. Diode83 passes these negative pulses and step by step charges capacitor 8negatively. Element 85 is a gaseous discharge tube, preferably of theregulator type. The anode 86 thereof is held at a predetermined positivepotential by means of a voltage divider 257, which is connected across asource of voltage as. Capacitor 89 is of relatively large value, forbypass purposes. When the cathode S6 of gaseous device 85 becomesslightly more negative than the potential which is requiredtoaccommodate three charge steps, tube 85 conducts and dischargescapacitor 84, causing the cycle to repeat. The waveform obtained isshown at 9B in Fig. 6.

Should positive synchronizing pulses be more readily available at thereceiver terminal 89 than the negative ones described, the device ofFig. 5 will operate if the terminals of diode 83, discharge tube 86, andbattery 88 are merely reversed. In this instance, the waveforms of Fig.6 are inverted. A positive voltage, of course, must still be retained atterminal 30, for the proper operation of the amplifying stage 49, as isknown in the art.

In order that the phase of the color change be maintained, I have foundthat a small amplitude of the color impulse derived from the transmittedsignal by other means in the receiver may also be best impressed atterminal 80. This causes each third pulse of waveform 95 to have anincreased amplitude, as at 91, insuring that the breakdown of tube 85will occur coincident therewith as the device is put into operation. Asin Fig. 2, an additional amplifier stage 49 is preferable for applyingthe waveform to the deflecting means of the cathode ray tube assembly,either directly or via. transformer 50.

Color phase may also be maintained by adding a high frequency burst or apulse derived from it at 91 in waveform 95 only once each field or atsome other infrequent interval. The increase in amplitude toward afourth step is always sufficient to operate discharge tube 85. Theprimary function of the color pulse is to insure that the receiver willlock into proper color phase with the transmitter when operation begins.

For a color system which utilizes a color change each field oftelevision scanning, the time scale of Fig. 6 is merely altered torepresent the duration of one field of television scanning betweenpulses, a value of 1/144 second often being used. The capacitor valuesin the device of Fig. 5 are increased a number of times over appropriatevalues for the previously described line color change embodiment andoperation is had for the field color change cycle.

Consideration of the method of this invention will reveal thatflat-topped rectangular waves are not imperative to proper functioningof the color change process, nor are exactly equal amplitudes of thestepped wave required. A decrease in amplitude means that the path 9,for instance, would not be deflected in as sharp a curve as shown. Thismay be tolerated as long as the upper truncated face of screen i8 isstill impacted (Fig. 1). In other words, the angle of incidence can varya reasonable amount without causing malfunctiom mg.

The relatively steep sides of step waveforms Si or 9% denote rapidwriting of the electron stream upon either of the two types of screensdescribed during the change from one color to another. Since theintensity of response of such screens is inversely proportional to thisspeed, the flyback traces of the electron stream will not be seen. Inthe dot sequential method the flyback occurs after each three dots ofcolor. In the line by line method this occurs at the end of each thirdline and in the frame sequential method at the end of each third frame.

Certain variants of the preferred embodiments are possible, but theapplicant has found that a one-shot relaxation device is unsuitable.Such a device dwells at either of two levels, not three as required.Attempts to synchronize a second such device to provide a third (sayintermediate) level are fraught with practical synchronizationdifiiculties.

Each of applicant's described embodiments and analogous variants areaccurately synchronized with pulses derived from the color changewaveforms.

Certain of the alternate constructions for this type of device disclosedin my copending applica-.

tion, Serial No. 137,365, may be utilized, specifically, theelectrostatic type lenses and electrostatic deflection means. Thesimplified magnetic lens may also be used as long as the deflection oftelevision scanning does not exceed a third of the lens diameter for theuncompensated type of con struction and operation.

It will be understood that the numerical values indicated are forillustrative purposes only, and are not to limit the scope of thisspecification nor the appended claims.

Having thus fully described my invention, I claim:

1. A sequential color television reproducing system comprising: a.cathode ray tube, means for producing an electron stream therein, meansfor deflecting said stream, a truncated ridged multiplanar screen in thepath of said electron stream, transducers attached to the planes of saidscreen, the characteristics of said transducers being alike on allplanes having the same inclination but being different on planes ofdifferent inclination, a dynamical electron lens for deflecting saidstream located near said screen relative to the location of said priordeflecting means, means for producing electrical energy variations insynchronism with television scanning, means for activating said priormeans and said dynamical lens therewith, means for producing electricalenergy variations in synchronism with changes in color components to bereproduced, means for forming and combining plural series of electricalpulses in synchronism therewith, a capacitor, means to apply said pluralseries of pulses to said capacitor for the variation of the electricalcharge thereof, means to apply said variations in charge to said priordeflecting means for the deflection of said electron stream, said lensbeing constituted when thus activated to cause said stream to impactsaid screen successively at closely adjacent areas that lie in differentplanes.

2. .A color television reproducer comprising in combination a cathoderay tube of the type wherein a screen of separate color phosphors upondifferently inclined planes exhibits different elemental colors uponbeing impacted by the electron stream of said tube arriving at saidscreen over different arcuate paths, separate circuits fordifierentiating color-determining signal energy, a circuit for reversingthe phase of one said differentiated signal energy, a circuit forcombining said differentiated and said reversed diiferentiated energiesas a peak value charge upon a capacitor, deflection means connected tosaid capacitor for deflecting said electron stream, means to produce amagnetic field approximately coaxial with said electron stream betweensaid deflecting means and said screen coacting with said deflectingmeans to produce said arcuate paths.

3. A color television system comprising in combination a cathode raytube having different phosphors for exhibiting different colors whichlie upon difierently inclined planes, means for deflecting andcontrolling the intensity of the electron stream of said tube todelineate a television picture, an additional circuit responsive tocolor- 7 determining signals pertaining to said picture, said circuitincluding plural differentiating cir. cuits for differentiating the sameplurality of said signals, means to combine said differentiated signals,a capacitor connected thereto to receive each of said signals as acharge, means to provide an essentially axial magnetic field positionedto infiuence said electron stream prior to impacting said phosphors,independent defiective means coactively connected to said capacitor andpositioned to affect said electron stream prior to said axial means, thecoact-ion of said latter two means causing said electron stream toimpact said phcsphors in closely adjacent areas over separate arcuatepaths in accordance with said colondetermining signals for reproducinga. color teleision picture.

4. A color television reproducing system com" prising in combination acathode ray tube of the type wherein the color image is exhibited upon ascreen of truncated triangular cross-section having differentcolor-producing phosphors on differently inclined planes and anessentially axial magnetic field influences the electron stream of saidtube before the stream reaches the screen, a circuit for reproducingless than the full plurality of color signals associated with said colorimage, separate circuits for differentiating each said signal, a circuitfor combining said thus-processed signals, said circuit including acapacitor and means for accumulating a charge on said capacitorproportional to the algebraic sum of said differentiated signals, meansto deflect the electron stream of said tube in accordance with thecharge on said capacitor, the combination of said defies-- tion and theinfluence of said axial field causing said stream to impact said screenin closely adiacent areas over separate arcuate paths upon differentphosphors thereof in accordance with said color signals for theformation of the color image.

5. A color television reproducing system comprising the combination of acathode ray tube of the type wherein the color image is exhibited on ascreen having different colored-light-producing phosphors on differentlyinclined planes and wherein an essentially axial magnetic fieldinfluences the electron stream of said tube after deflection thereof andbefore reaching said screen, with means for reproducing less than thefull plurality of color-determining signals associated with said colorimage, separate circuits for differentiating each said signal, a circuitfor reversing the phase of one differentia1 signal, a circuit forcombining all said differentiated signals, a capacitor in said circuitaccepting each said differentiated signal as a charge, isolating meansassociated with said capacitor to retain said charge substantiallyundiminished until such time as the next differentiated signal arrives,means for deflecting said electron stream in proportion to said charge,said axial field coacting therewith to deflect said stream in a separatearcuate path for each differentiated signal for the period of time untilthe next said differentiated signal, said stream impacting a single kindof phosphor during said period.

6. A color television reproducing system comprising in combination acolor cathode ray tube of the type wherein the color image is exhibitedon a screen having different color phosphors on inclined planes ofdifferent inclination and at least one dimension of the order of pictureelement size by a deflected electron stream subsequent to deflectiontraversing a magnetic field substantially coaxial with said electronstream before impinging upon said screen, a circuit for reproducingplural series of electrical energy variations in synchronisni withchanges in excitation required from one to another of said difierentphosphors according to the color image to be reproduced, separatecircuits for differentiating each series, a circuit for combining saiddifferentiated series in such relative phase that more differentiatedvariations of one polarity than of the opposite polarity occur in theresulting series, a capacitor connected to said circuit to assume acharge proportional to said combined differentiated variations, saidcapacitor sufficiently isolated in said circuit to substantially retainthe peak value of one difierentiated vari ation until the peak value ofthe succeeding variation of the combined series occurs, means foradditionally deflecting said electron stream in accordance with thevalue of said charge, said coaxial field coacting with said stream todeflect the same in a unique arcuate path for each said charge, saidstream impacting a single phosphor during the time said charge persistsfor the element by element formation of the color image.

HARRY R. LUBCKE.

References Cited in the his of this patent UNITED STATES PATENTS

